Virtual private local area network service (VPLS) is a multipoint-to-multipoint (MP-MP) service, which emulates local area network (LAN) functionality over provider networks. VPLS is described, for example, by Augustyn and Serbest in “Service Requirements for Layer 2 Provider-Provisioned Virtual Private Networks,” Internet Engineering Task Force (IETF) RFC 4665, September, 2006; by Lasserre and Kompella in “Virtual Private LAN Services Using LDP,” IETF Internet draft draft-ietf-12vpn-vpls-ldp-09, June, 2006; and by Kompella and Rekhter in “Virtual Private LAN Service (VPLS) Using BGP for Auto-discovery and Signaling,” IETF Internet draft draft-ietf-12vpn-vpls-bgp-08, June, 2006, which are incorporated herein by reference. These documents, as well as other IETF documents cited herein, are available on-line at www.ietf.org.
VPLS is sometimes deployed over ring networks. An exemplary ring architecture is the Resilient Packet Ring (RPR) protocol, which is defined in IEEE standard 802.17-2004, entitled “Part 17: Resilient Packet Ring (RPR) Access Method & Physical Layer Specifications,” June, 2004, which is incorporated herein by reference. The 802.17 standard is available at www.standards.ieee.org/getieee802/802.17.html.
The use of VPLS over ring networks is described, for example, in U.S. Patent Application Publication 2006/0109802, whose disclosure is incorporated herein by reference. This publication describes a method for communication via a ring network that includes a plurality of nodes. The method includes receiving at a first node in the ring network a data packet transmitted over a virtual private LAN service (VPLS), the data packet including an identification of the VPLS. The first node reads the identification from the data packet. Responsively to reading the identification, the first node forwards the data packet to at least one second node in the ring network that is associated with the VPLS.
Some point-to-point services provide signaling mechanisms for reporting status to remote peers. Status signaling mechanisms used in pseudowire (PW) services are described, for example, by Martini et al., in IETF RFC 4447, entitled “Pseudowire Setup and Maintenance Using the Label Distribution Protocol (LDP),” April, 2006, section 5.4.2, and by Martini in IETF RFC 4446 entitled “IANA Allocations for Pseudowire Edge to Edge Emulation (PWE3),” April, 2006, section 3.5, both of which are incorporated herein by reference.